Explanation

• An Addition Reaction is a chemical reaction in which two or more substances combine to form a single compound.
• It is also called a Combination Reaction in basic chemistry.
• This reaction usually releases heat or energy.

Last verified on 12-03-2026

Explanation

• A chemical reaction that releases heat energy to the surroundings is called an Exothermic Reaction.
• In such reactions, energy is produced in the form of heat, light, or flames.
• Examples include combustion of fuel, respiration, and neutralization reactions.

Additional information:

• An endothermic reaction, which absorbs heat from the surroundings.

Last verified on 11-03-2026

Explanation

• The branch of chemistry that studies heat energy released or absorbed during chemical reactions is called Thermochemistry.
• It explains how heat changes occur during reactions such as combustion, neutralization, and dissolution.
• It deals with concepts like enthalpy change (ΔH), exothermic reactions, and endothermic reactions.

Last verified on 11-03-2026

Explanation

• The formation of hydrogen and oxygen from water, which is an example of a decomposition reaction: 2H2O → 2H2 + O2
• In this reaction, water (H2O) decomposes into hydrogen (H2) and oxygen (O2).

Last verified on 11-03-2026

Explanation

• Antoine Lavoisier, a French chemist, is credited with discovering the law of conservation of mass in 1789 (1785).
• He demonstrated that matter cannot be created or destroyed in a chemical reaction, only transformed from one substance to another.

Last verified on 10-03-2026